Given a sequence of integers as an array, determine whether it is possible to obtain a strictly increasing sequence by removing no more than one element from the array.
Example
-
For
sequence = [1, 3, 2, 1]
, the output should bealmostIncreasingSequence(sequence) = false
.There is no one element in this array that can be removed in order to get a strictly increasing sequence.
-
For
sequence = [1, 3, 2]
, the output should bealmostIncreasingSequence(sequence) = true
.You can remove
3
from the array to get the strictly increasing sequence[1, 2]
. Alternately, you can remove2
to get the strictly increasing sequence[1, 3]
.
Input/Output
-
[execution time limit] 0.5 seconds (cpp)
-
[input] array.integer sequence
Guaranteed constraints:
2 ≤ sequence.length ≤ 105
,-105 ≤ sequence[i] ≤ 105
. -
[output] boolean
- Return
true
if it is possible to remove one element from the array in order to get a strictly increasing sequence, otherwise returnfalse
.
- Return
C++解法:
1 bool isSequence(vector<int> sequence) 2 { 3 set<int>iset; 4 for(auto e: sequence) 5 iset.insert(e); 6 if(iset.size() != sequence.size()) //如果sequence中有重复元素,返回false 7 return false; 8 9 vector<int>v = sequence; //如果sequence与排序后的v相等,则说明sequence是递增有序的 10 sort(v.begin(), v.end()); 11 if(sequence == v) 12 return true; 13 else 14 return false; 15 16 } 17 18 bool almostIncreasingSequence(std::vector<int> sequence) 19 { 20 if (isSequence(sequence)) 21 return true; 22 int i = 0; 23 while (i < sequence.size()) 24 { 25 vector<int> v = sequence; 26 v.erase(v.begin() + i); 27 if(isSequence(v)) 28 return true; 29 ++i; 30 } 31 return false; 32 }